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Lecture 16

HMB200 2014 Lecture 16.pdf
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Department
Human Biology
Course
HMB200H1
Professor
John Yeomans
Semester
Winter

Description
  Lecture  16:  Emotions  and  Limbic  System   Limbic  System   • Closest  connection  with  olfactory  system  and  hypothalamus   • Oldest  areas  of  telencephalon,  bordering  diencephalon.  Limbic  means  "border".     • telencephalon:  olfactory  processing,  sex  and  emotional  behavior     • Starts  at  non  cortical  area  to  cortical  olfactory  areas  and   cortical  limbic  areas   • Limbic  =  border  à  areas  that  border  the  diencephalon,   underneath  the  cerebral  cortex   • Important  in  human  mental  diseases   • Unlike  cerebral  cortex,   limbic  system  has  DIRECT  connections  with   olfactory  and  taste  systems,  hypothalamus  (visceral  &  emotional).   • Strong  connection  with  dopamine  system  (motivation  of   behavior)   • Areas  bordering  the  diencephalon   • Has  direct  connections  with  visceral  systems  (olfac tory  and   taste)  and  direct  connection  with  hypothalamus   (visceral   integration  system)   • Limbic  system  areas  can  be  grouped  into  2  categories:   • Transition  from  subcortex  (e.g.  amygdala)  to  3 -­‐4  layered   cortex  (e.g.  hippocampus)  to  6-­‐layered  neocortex.   1) oldest  areas:  subcortical  areas  (closely  connected  with  the   hypothalamus  and  amygdala),  includes  amygdala  nuclei,  nuclei  accumbens  (Reward  behaviors)   ventral  pallidum,  BNST  –  non  cortical  deep  limbic  system  structures     2) cortical  structures:  amygdala  (at  the  anterior  tip  of  the  hippocampus),  deep  temporal  lobe  structures,   olfactory  bulb  (connects  with  amygdala  and  entorhinal  cortex),  hippocampal  area  continues   connections  with  the  Cingular  gyrus  and  forebrain  (to  frontal  cortex   –  basal  forebrain  nuclei,  limbic   frontal  cortex  structures)   • Interconnections:  "Papez  Circuit"     Subcortical  Limbic  Systems  (Extended  Amygdala)   -­‐  interconnected   • Amygdala   • Emotion  and  emotional  learning   • Basal  Forebrain  Nuclei  (Ch1 -­‐4)   • Bed  Nucleus  of  Stria  Terminalis   • Sex  and  gender   • Ventral  Pallidum   • Pair  boding  with  vasopressin  next  to  nucleus  accumbens   • Septum   • Nucleus  Accumbens  (Ventral  Striatum)   • Important  in  emotional  behaviours   • Olfactory  Tubercle   o These  are  closely  collected  subcortical  structures   o Heimer:  all  of  these  structures  can  be  identified  becau se  they  all  have  direct  connections  to  amygdala  (major   output  for  emotional  behaviours)   –  extended  amygdala   • Can  be  associated  with  the  olfactory  system   –  rhinecephalon   • Rhinecephalon  emphasizes  that  these  structures  also  have  connections  with  olfactory  syst em     o These  are  the  oldest,  most  primitive  areas  of  the  forebrain     Cortical  Limbic  Systems  (higher  limbic  systems)   • Hippocampus     • hippocampus:  highly  structured  and  highly  layered   –  important  for  emotional  learning  à  declarative   memories  and  cognitive  learning   • from  emotional  system  to  high  cognitive  processing  system  for  memory   • Connected  with  hippocampus   –  closely  connected  temporal  lobe  structure:  subiculum  and   parahippocampal  areas  à  extend  right  out  of  hippocampus   • Subiculum   • Entorhinal  Cortex       • olfactory  processing  and  spatial  maps   • Cingulate  Cortex   • Extends  upward  from  hippocampus,  up  to  parietal  lobe,  above  the  corpus  collosum   • Insular  Cortex   • Orbitofrontal  Cortex   • (Dorsolateral  Frontal  Cortex)   o As  these  structures  grow,  they  pull  underlying  into  c  shape  structure   • Temporal  pole  à  cingular  gyrus  à  orbital  frontal  cortex  (most  anterior  tip  of  the  C)     • Temporal  lobe  structures   à  parietal  lobe  structures   à  frontal  lobe  structures  as  we  follow  the  C   o C  shape  structure:  all  brain  structure  form  layers  in  C  shape  structure       Limbic  system  and  Emotion   -­‐ just  above  the  eyeball,  the  orbital  frontal  cortex  –  limbic  frontal  cortex  just  in  front  of  basal  forebrain   o important  in  emotional  processing   -­‐ just  above  this,  anterior  cingulate  cortex ,  important  in  depression  and  emotional  processing   -­‐ behind  that  is  the  posterior  circulate,  continues  into  temporal  lobe   -­‐ 2  areas  of  temporal  lobe  that  are  important   à  amygdala  and  just  above  it  is  the  sylvian  fissure  (divides  temporal   and  parietal  lobe)   o inside  the  Sylvian  Fissure  is  the  Insular  Cortex  –  visceral  cortex  important  for  taste  processing  and   olfactory  decision  making  à  makes  emotional  decisions     Early  Studies   • Temporal  lobe  lesions  (Klüver -­‐Bucy  Syndrome)  lead  to  tame  monkeys,  fearless  and  hypersexual.   • Seizures  associated  with  temporal  lobe   • Temporal  lobe  epilepsy  leads  to  emotional  auras  and  behaviors.   • Tumors  or  scar  tissue  in  temporal  lobe:  strange  emotional  auras  followed  by  loss  of  consciousness   (Feelings  of  panic  and  anger)   • Temporal  lobe  removed?  Strange  behaviors  of  fearlessness  (monkeys  lose  understanding  of  social  hierarchy)   –  less   fearful  of  humans  à  become  tamed  in  presence  of  humans   • Strange  social  responses  and  hypersexual  (mount  poles)   • Social  relationships  and  emotional  behavior  dependent  on  temporal  lobe?   •  Stimulation  of  amygdala  lea ds  to  attack,  rage  or  positive  affect.   • Electrically  stimulate  amygdala:  produce  same  feelings  in  temporal  lobe  epilepsy   • Local  stimulation  of  amygdala:  sexual  feelings,  rage,  attack   –  very  intense  emotional  feelings  without   awareness  of  circumstances   • amygdala  important  in  violent  behavior?  No.  But  activation  of  it  will  produce  violence   • important  for  uncontrollable,  undefined  emotional  response  behaviors   • Stimulation  of  hippocampal  region  leads  to  experiential  reports  "deja  vu".  (Penfield)   • Deep  personal  feelings  à  personal  events  in  early  life   à  déjà  vu  reports   • Especially  in  left  temporal  lobe   à  reports:  delusional  reports  of  something  in  the  past  (Feel  as  if  they  are   transported  back)     Conditioned  Fear  Paradine   • Tone  (Conditioned  stimulus)     • In  rodents,  discovered  amygdala  is  important  for  learned  (Conditioned)  fear   • Involves  discrete  pathways  that  go  to  amygdala  that  induce  defensive  responses  in  brain  stem   • Neutral  stimuli  and  fearful  stimuli  occurs  in  lateral   nucleus  of  amygdala   • Conditioned  stimuli  (tone)  presented  alone  and  produces  small  response   • This  is  then  paired  with  an  unconditioned  stimulus   (usually  weak  shock)   • Shock  (Unconditioned  stimulus)   • Unconditioned  stimuli  produces  uncomfortable   response  in  animal   • Fear  Responses:  Increased  heart  rate,  Increas
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